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C Mitsiades

Publications and source records attributed to C Mitsiades.

10 recordsLinked to original sources
PubMed2004

2-Methoxyestardiol and bortezomib/proteasome-inhibitor overcome dexamethasone-resistance in multiple myeloma cells by modulating Heat Shock Protein-27.

Multiple myeloma (MM) remains fatal despite all available therapies. Initial treatment with conventional drugs such as, Dexamethasone (Dex) effectively induces MM cell death; however, prolonged drug exposures results in the development of chemoresistance. Our prior study demonstrated that 2-Methoxyestradiol (2ME2) induces apoptosis in multiple myeloma (MM) cells resistant to Dexamethasone (Dex). Here, we show the mechanism whereby 2ME2 overcomes Dex-resistance. The oligonucleotide array analysis demonstrates that Heat Shock Protein-27 (Hsp27) is upregulated in Dex-resistant, but not in Dex-sensitive MM cells. Proteomics analysis of Hsp27-immunocomplexes revealed the presence of actin in Dex-resistant, but not in Dex-sensitive cells. Biochemical interaction between Hsp27 and actin was examined by co-immunoprecipitation with anti-Hsp27 or actin Abs. Far western blot analysis using GST-Hsp27 fusion protein showed a direct association with actin both in vitro and in vivo. Importantly, 2ME2- or Bortezomib/Proteasome inhibitor (PS-341)-induced apoptosis in Dex-resistant MM cell lines and MM patient cells is associated with disruption of the Hsp27-actin complexes. Finally, blockade of Hsp27 by anti-sense strategy enhanced anti-MM activity of both 2ME2 and PS-341. These findings provide the clinical application of novel therapeutics targeting Hsp27 to improve patient outcome in MM.

2-Methoxyestradiol↗
PubMed2003

Endocrine/paracrine/autocrine survival factor activity of bone microenvironment participates in the development of androgen ablation and chemotherapy refractoriness of prostate cancer metastasis in skeleton.

Bone is the most frequent site of metastases of prostate cancer and is almost always the first and frequently the only site of metastases where disease will progress to stage D3. In addition, the number of skeletal metastatic foci is the most powerful independent prognostic factor of limited response to hormone ablation therapy and poor survival of patients with advanced prostate cancer. Furthermore, disease progression frequently occurs in the osteoblastic metastases, even though androgen ablation therapy still provides adequate and sustained control of disease at the primary site. Notably, the management of metastatic disease onto bones has traditionally relied on therapeutic modalities, which almost exclusively aim at directly inducing cancer cell death. However, accumulating pieces of evidence, from both the clinical and the basic research front, point to major limitations of this conventional approach. The in vivo response of malignant cells to anticancer therapies is directly influenced by the local microenvironment in which they metastasize. In particular, organ sites frequently involved in metastatic diseases, such as the bones, appear to confer to metastatic cells protection from anticancer drug-induced apoptosis. This protection is mediated by soluble growth factors and cytokines released by the normal cellular constituents of the host tissue microenvironment. The characterization of bone microenvironment-related survival factors has led to the development of a novel hormone manipulation which can re-introduce clinical responses in patients with stage D3 prostate cancer.

Androgen Antagonists↗
PubMed2001

Vascular endothelial growth factor triggers signaling cascades mediating multiple myeloma cell growth and migration.

Multiple myeloma (MM) remains incurable, with a median survival of 3 to 4 years. This study shows direct effects of vascular endothelial growth factor (VEGF) upon MM and plasma cell leukemia (PCL) cells. The results indicate that VEGF triggers tumor cell proliferation via a protein kinase C (PKC)-independent Raf-1-MEK-extracellular signal-regulated protein kinase pathway, and migration via a PKC-dependent pathway. These observations provide the framework for novel therapeutic strategies targeting VEGF signaling cascades in MM.

Cell Division↗
PubMed2001

Ewing's sarcoma family tumors are sensitive to tumor necrosis factor-related apoptosis-inducing ligand and express death receptor 4 and death receptor 5.

In this study, we investigated the sensitivity of Ewing's sarcoma family tumors (ESFTs) of children and adolescents to the tumor necrosis factor-related apoptosis-inducing Ligand (TRAIL). TRAIL binds to death receptors (DRs) DR4, DR5, DcR1, and DcR2. Either DR4 or DR5 can induce apoptosis, whereas DcR1 and DcR2 are considered inhibitory receptors. Nine of 10 ESFT cell lines, including several that were Fas resistant, underwent apoptosis with TRAIL through activation of caspase-10, capase-8 (FLICE), caspase-3, and caspase-9. In contrast to the Fas signaling pathway, caspase-10, but not caspase-8 or the Fas-associated death domain-containing molecule, was recruited to the TRAIL receptor-associated signaling complex. We found that 9 of 10 ESFT cell lines expressed both DR4 and DR5 by Western blotting, whereas the TRAIL-resistant line expressed only DR4. However, DR4 was absent from the cell surface in the resistant and two additional lines (three of five tested lines), suggesting that it may have been nonfunctional. On the contrary, DR5 was located on the cell surface in all four sensitive lines tested, being absent only from the cell surface of the resistant line that was also DR5-negative by Western blotting. In agreement with these findings, the resistance of the line was overcome by restoration of DR5 levels by transfection. Levels of DcR1 and DcR2 or levels of the FLICE-inhibitory protein (FLIP) did not correlate with TRAIL resistance, and protein synthesis inhibition did not sensitize the TRAIL-resistant line to TRAIL. Because these data suggested that sensitivity of ESFTs to TRAIL was mainly based on the presence of DR4/DR5, we investigated the presence of these receptors in 32 ESFT tissue sections by immunohistochemistry. We found that 23 of 32 tumor tissues (72%) expressed both receptors, 8 of 32 (25%) expressed one receptor only, and 1 was negative for both. Our finding of wide expression of DR4/DR5 in ESFT in vivo, in combination with their high sensitivity to TRAIL in vitro and the reported lack of toxicity of TRAIL in mice and monkeys, suggests that TRAIL may be a novel effective agent in the treatment of ESFTs.

Apoptosis↗
PubMed2001

A combination therapy of dexamethasone and somatostatin analog reintroduces objective clinical responses to LHRH analog in androgen ablation-refractory prostate cancer patients.

We evaluated whether the combination of triptorelin, a LHRH analog (LHRH-A), with dexamethasone and lanreotide, a somatostatin analog, can produce objective clinical responses in metastatic androgen ablation-refractory prostate cancer (stage D3) patients who have relapsed, after combined androgen blockade (LHRH-A plus antiandrogen) and antiandrogen withdrawal. Eleven stage D3 patients with diffuse bony metastases, who had progressed despite initial responses (lasting <12 months) to combined androgen blockade therapy and subsequently failed antiandrogen withdrawal, received oral dexamethasone (4 mg daily for the first month, tapered down to 2 mg after the first month and 1 mg after the second month, and continued on 1 mg thereafter) and lanreotide (30 mg im every 14 d) in combination with triptorelin (3.75 mg im every 28 d). Serum prostate-specific antigen, alkaline phosphatase, performance status, and bone pain were assessed monthly during therapy. Fasting blood glucose was measured biweekly, and serum IGF-I, T, and dehydroepiandrosterone sulfate levels were assessed at baseline, at response to the combination therapy, and at relapse from it. Ten of 11 stage D3 patients [90.9% of patients; 95% confidence interval (CI), 58.7-99.8%] had durable objective clinical responses (including > or = 50% prostate-specific antigen decline in 8 patients, 72.7%; 95% CI, 39-94%). All patients reported significant and durable improvement of bone pain (for a median duration of 13 months; 95% CI, 12-14 months; range, 6-22 months) and performance status (median duration, 19 months; 95% CI, 13-25 months; range, 7-22 months) without major treatment-related side effects. The median progression-free survival was 7 months (95% CI, 4-10 months; range, 3-17 months), and the median overall survival was 18 months (95% CI, 16-20 months; range, 7-22 months). Five of six total deaths occurred secondary to disease progression. We observed a statistically significant (P = 0.018) reduction in serum IGF-I levels at response to the combination therapy (60% reduction of baseline IGF-I levels). Dehydroepiandrosterone sulfate levels, although already significantly suppressed at baseline, had an additional significant reduction (P < 0.02) at response to therapy. T levels remained suppressed within castration levels (<3 nmol/liter, at baseline and throughout therapy, including relapse). The combination therapy of LHRH-A with dexamethasone plus somatostatin analog produces objective clinical responses and symptomatic improvement in androgen ablation (LHRH-A) refractory prostate cancer patients.

Aged↗
PubMed2000

Three-dimensional type I collagen co-culture systems for the study of cell-cell interactions and treatment response in bone metastases.

The available monolayer culture systems for the study of bone metastases constitute a suboptimal simulation of the in vivo pathophysiology of bone metastases, and therefore, do not provide sufficient information to assess the morphologic evidence of bone reaction to cancer cells, the nature of cell-specific mediators of osteolysis and osteoplasia and the response to treatment. Therefore, we have developed a three-dimensional (3-D) type I collagen gel system that allows co-culture of human osteoblasts (MG-63) with cancer cells, such as MCF-7, MDA-MB-231 or ZR-75 breast cancer cells, PC-3 prostate cancer, KLE endometrial cancer cells and Calu-1 lung cancer cells. We used type I collagen purified from rat tail tendons and the 3-D system was prepared by mixing MG-63 cells with type I collagen in 24-well plates. The 3-D system was inoculated with cancer cells and processed with standard cell culture procedures. After 1 week of culture, the matrix gel was fixed with formalin and embedded in paraffin. Serial sections were stained with trichrome Masson stain and modified Masson-Goldner stain, as well as analyzed by in situ hybridization, immunohistochemistry and the TUNEL technique for semi-quantitative detection of apoptotic cell death, assessing the response to adriamycin therapy. The inoculation of PC-3 cells in this collagen matrix produced a blastic reaction, documented by an increased number of MG-63 cells and increased density of type I collagen. The human KLE cells and inoculation of cell-free media produced no reaction, while ZR-75, MCF-7 and Calu-1 cells produced local degradation of the collagen matrix. In situ hybridization revealed the expression of Insulin-like growth factor 1 (IGF-1) and urokinase-type plasminogen activator (uPA) mRNA, while immunohistochemistry detected differential expression of uPA and cathepsin D. Adriamycin induced apoptotic cell death in prostate cancer cells and estrogen receptor negative (ER-) MDA-MB-231 breast cancer cells, while adriamycin did not induce apoptosis but cytostasis in ER+ MCF-7 cells. The adriamycin-induced apoptosis was inhibited by co-culture with osteoblast-like cells (MG-63). We conclude that this 3-D culture system is a useful in vitro model allowing the analysis of local mediators of osteolytic and osteoblastic reactions to bone metastases and treatment response.

Journal Article↗
PubMed2000

Cancer and bone repair mechanism: clinical applications for hormone refractory prostate cancer.

It is a long-standing clinical observation that the bone corresponds to the prevalent site for metastatic growth of prostate cancer. In addition, bone metastases of this malignancy produce a potent blastic reaction, in contrast to the overwhelming majority of other osteotropic neoplasms, whose metastases are generally associated with an osteolytic reaction. Osteoblastic metastases represent almost always the first and, frequently, the exclusive site of disease progression to hormone refractory stage, stage D3. Moreover, the number of skeletal metastatic foci is the most powerful independent prognostic factor associated with a limited response to hormone ablation therapy and poor survival of advanced prostate cancer. It is noteworthy that disease progression to hormone refractory stage occurs almost always in osteoblastic metastases. These clinical observations suggested that the osteoblastic reaction is possibly not an innocent bystander of the metastatic prostate tumour growth, simply suffering its consequences, but it may in fact facilitate the efforts of metastatic cells to expand their population. An extensive line of research in the pathophysiology of osteoblastic metastases has established that the local blastic reaction involves the uPA/plasmin/IGF/IGFBP-3/TGFbs bioregulation system which can stimulate both the growth of osteoblasts and prostate cancer cells. Furthermore, we were the first to characterize osteoblast-derived 'survival factors' able to rescue metastatic prostate cancer cells from chemotherapy-induced apoptosis. These data resulted in the development of a novel concept of an anti-survival factor therapy, namely an anti-IGF-1 therapy, which has provided encouraging preliminary data in a phase II clinical trial with terminally-ill hormone/chemotherapy-resistant prostate cancer patients.

Journal Article↗
PubMedDate not supplied

Tumor cell expression of CD59 is associated with resistance to CD20 serotherapy in patients with B-cell malignancies.

The anti-CD20 chimeric monoclonal antibody rituximab (Rituxan) is used to treat patients with various B-cell tumors, including patients with plasma cell dyscrasias who have CD20+ disease. Many patients with CD20+ disease have either primary unresponsive disease or progress after initially responding to rituximab; therefore, understanding how tumor cells are, or become, resistant to rituximab is of clinical relevance. In this report, we determined whether tumor cells express antigens that block complement-mediated lysis or antibody-dependent cell-mediated cytotoxicity (ADCC) and thereby contribute to rituximab resistance. We demonstrate that expression of the complement regulator CD59 is associated with resistance to rituximab-mediated complement lysis of multiple myeloma (MM) and non-Hodgkin's lymphoma (NHL) cell lines. Moreover, neutralization of CD59 using a blocking monoclonal antibody reversed resistance to rituximab-mediated complement lysis of CD20++ CD59++ ARH-77 MM cells. In addition, we demonstrate the presence of CD59 and rituximab binding on viable tumor cells from patients with MM and Waldenstrom's macroglobulinemia with progressive disease despite rituximab therapy. Last, we also examined MM and NHL B-cell lines, as well as patient tumor cells, for the expression of other antigens that may have a role in blocking ADCC activity, such as Fas ligand (FasL), MUCI, or TRAIL. FasL, MUC1, and/or TRAIL were coexpressed with complement regulators on many of these cells. These studies therefore show that complement regulators, particularly CD59 and antigens that may block ADCC, are present on various B-cell tumors and associated with rituximab resistance in patients. A prospective, clinical study is assessing the role of these antigens in mediating rituximab resistance.

Animals↗
PubMedDate not supplied

Conversion of nested reverse-transcriptase polymerase chain reaction from positive to negative status at peripheral blood during androgen ablation therapy is associated with long progression-free survival in stage D2 prostate cancer patients.

BACKGROUND: Nested reverse-transcriptase polymerase chain reaction (nested rt-PCR) for the detection of mRNA of prostate specific antigen (PSA) and prostate specific membrane antigen (PSMA) in peripheral blood samples (PB) and bone marrow biopsies (BM) can assess the extraprostatic growth of prostate cells. MATERIALS AND METHODS: Nested rt-PCR for PSA and PSMA at PB and BM was performed (a) at diagnosis, (b) after 6 months from the initiation of combined androgen blockade [(CAB); triptorelin 3.75 mg, i.m., q28 days plus flutamide 250 mg, per os, tid] and, (c) at progression to androgen refractory stage in 28 patients with newly-diagnosed stage D2 prostate cancer. RESULTS: At diagnosis, all patients were found to be rt-PCR positive for PSA and PSMA at BM while 7 (25%) were rt-PCR negative for PSA and PSMA at PB. Nine out of 21 patients with rt-PCR-positive status have converted to rt-PCR-negative status at PB during CAB while they remained rt-PCR-positive at BM. The rt-PCR-negative status at PB during CAB was associated with progression-free survival >12 months (p=0.029). At progression to androgen refractory stage all but 2 patients were rt-PCR-positive at PB for PSA and PSMA, among them 3 who were rt-PCR-negative at diagnosis. CONCLUSION: Our data suggest that conversion to rt-PCR-negative status at PB for PSA and PSMA during objective clinical response to CAB is associated with long progression-free survival in stage D2 disease.

Androgen Antagonists↗